U.S. patent application number 13/980066 was filed with the patent office on 2013-10-31 for base station and communication control method.
This patent application is currently assigned to NTT DOCOMO, INC.. The applicant listed for this patent is Minami Ishii, Toshihisa Sekikawa, Tadashi Uchiyama. Invention is credited to Minami Ishii, Toshihisa Sekikawa, Tadashi Uchiyama.
Application Number | 20130286829 13/980066 |
Document ID | / |
Family ID | 47071964 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130286829 |
Kind Code |
A1 |
Ishii; Minami ; et
al. |
October 31, 2013 |
BASE STATION AND COMMUNICATION CONTROL METHOD
Abstract
A base station includes a congestion state determination unit
that determines whether the base station is in a congestion state;
a barring target setting unit that sequentially sets targets of
barring among a plurality of the targets of the barring when a
determination is made that it is the congestion state; a barring
time interval setting unit that sets a time interval of the barring
based on the congestion state when the determination is made that
it is the congestion state; and a transmitter that transmits
information representing the targets of the barring and information
representing the time interval of the barring to the user
equipment.
Inventors: |
Ishii; Minami; (Chiyoda-ku,
JP) ; Uchiyama; Tadashi; (Chiyoda-ku, JP) ;
Sekikawa; Toshihisa; (Chiyoda-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ishii; Minami
Uchiyama; Tadashi
Sekikawa; Toshihisa |
Chiyoda-ku
Chiyoda-ku
Chiyoda-ku |
|
JP
JP
JP |
|
|
Assignee: |
NTT DOCOMO, INC.
Tokyo
JP
|
Family ID: |
47071964 |
Appl. No.: |
13/980066 |
Filed: |
March 27, 2012 |
PCT Filed: |
March 27, 2012 |
PCT NO: |
PCT/JP2012/058019 |
371 Date: |
July 17, 2013 |
Current U.S.
Class: |
370/230 |
Current CPC
Class: |
H04W 28/0205 20130101;
H04W 68/00 20130101; H04W 88/08 20130101; H04W 48/06 20130101 |
Class at
Publication: |
370/230 |
International
Class: |
H04W 48/06 20060101
H04W048/06 |
Claims
1. A base station that performs radio communication with user
equipment, the base station comprising: a congestion state
determination unit that determines whether the base station is in a
congestion state; a barring target setting unit that sequentially
sets targets of barring among a plurality of the targets of the
barring when the congestion state determination unit determines
that the base station is in the congestion state; a barring time
interval setting unit that sets a time interval of the barring
based on the congestion state when the congestion state
determination unit determines that the base station is in the
congestion state; a notification information generating unit that
generates information for transmitting information which represents
the targets of the barring and information which represents the
time interval of the barring, wherein the targets of the barring
are to be set by the barring target setting unit, and the time
interval of the barring is to be set by the barring time interval
setting unit; and a transmitter that transmits the information
generated by the notification information generating unit to the
user equipment.
2. The base station according to claim 1, wherein the barring
target setting unit selects the targets of the barring among a
cell, a type of a call, and a type of the user equipment.
3. The base station according to claim 2, wherein, when the barring
target setting unit selects the cell as the target of the barring,
the barring target setting unit specifies the cell by at least one
of a frequency and an identifier of the cell, wherein the cell is
to be barred.
4. The base station according to claim 2, wherein, when the barring
target setting unit selects the type of the call as the target of
the barring, the barring target setting unit specifies the type of
the call by at least one of a mobile originated call from the user
equipment, mobile originated signaling from the user equipment, and
a circuit switch service, wherein the type of the call is to be
barred.
5. The base station according to claim 2, wherein, when the barring
target setting unit selects the type of the user equipment as the
target of the barring, the barring target setting unit specifies
the user equipment by at least one of the user equipment of a
general user, the user equipment of a user who is preferentially
connected, and the user equipment of a person who performs
maintenance, wherein the type of the user equipment is to be
barred.
6. The base station according to claim 1, wherein the notification
information generating unit generates system information including
information for transmitting a paging message which includes
information indicating that broadcast information is modified;
information which represents the targets to be barred, wherein the
targets to be barred are to be set by the barring target setting
unit; and information representing the time interval of the
barring, wherein the time interval of the barring is to be set by
the barring time interval setting unit.
7. A communication control method of a base station that performs
radio communication with user equipment, the communication control
method comprising: a congestion state determination step of
determining whether the base station is in a congestion state; a
barring target setting step of sequentially setting targets of
barring among a plurality of the targets of the barring when the
congestion state determination step determines that the base
station is in the congestion state; a barring time interval setting
step of setting a time interval of the barring based on the
congestion state when the congestion state determination step
determines that the base station is in the congestion state; a
notification information generating step of generating information
for transmitting information which represents the targets of the
barring and information which represents the time interval of the
barring, wherein the targets of the barring are to be set by the
barring target setting step, and the time interval of the barring
is to be set by the barring time interval setting step; and a
transmission step of transmitting the information generated by the
notification information generating step to the user equipment.
Description
TECHNICAL FIELD
[0001] The present invention relates to a radio communication
system.
BACKGROUND ART
[0002] The specifications of Long Term Evolution (LTE) have been
developed by a standardization organization of mobile communication
systems, which is 3rd Generation Partnership Project (3GPP). LTE
achieves high-speed communication, where 100 Mbps or more is
achieved for a downlink and 50 Mbps or more is achieved for an
uplink. For LTE, attempts are made to improve the latency and
frequency utilization efficiency.
RELATED ART DOCUMENT
Non-Patent Document
[0003] 3GPP TS 36.331 V10.0.0 (5.2 System information 5.2.1
Introduction) 2010-12
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0004] Due to concentration of access from user terminals (user
equipment), it is possible that load is increased and congestion
occurs in a base station (eNodeB). Specifically, congestion in a
device is assumed for a case where access is concentrated due to an
event such as a new year event; a case where access is concentrated
due to occurrence of a disaster; a case where access is
concentrated due to occurrence of an accident; and a case where
access is concentrated during activation of a base station.
Depending on an extent of the congestion, the base station may not
operate normally. In the worst case, it is possible that a packet
is lost in the base station or state of the base station becomes an
operation shutdown mode.
[0005] An object of the disclosed base station is to reduce the
load.
Means for Solving the Problem
[0006] The disclosed base station according to one embodiment is a
base station that performs radio communication with user equipment.
The base station includes a congestion state determination unit
that determines whether the base station is in a congestion state;
a barring target setting unit that sequentially sets targets to be
barred among a plurality of the targets to be barred when the
congestion state determination unit determines that the base
station is in the congestion state; a barring time interval setting
unit that sets a time interval during which the barring is to be
performed based on the congestion state, when the congestion state
determination unit determines that the base station is in the
congestion state; a notification information generating unit that
generates information representing the targets to be barred and
information representing the time interval of the barring, wherein
the targets to be barred are to be set by the barring target
setting unit and the time interval of the barring is to be set by
the barring time interval setting unit; and a transmitter that
transmits the information which is generated by the notification
information generating unit to the user equipment.
[0007] The disclosed communication control method according to one
embodiment is a communication control method of a base station that
performs radio communication with user equipment. The communication
control method includes a congestion state determination step of
determining whether the base station is in a congestion state; a
barring target setting step of sequentially setting targets to be
barred among a plurality of the targets to be barred when the
congestion state determination step determines that the base
station is in the congestion state; a barring time interval setting
step of setting a time interval during which barring is to be
performed based on the congestion state when the congestion state
determination step determines that the base station is in the
congestion state; a notification information generating step of
generating information representing the targets to be barred and
information representing the time interval of the barring, wherein
the targets to be barred are to be set by the barring target
setting step and the time interval of the barring is to be set by
the barring time interval setting step; and a transmitting step of
transmitting the information which is generated by the notification
information generating step to the user equipment.
Effect of the Present Invention
[0008] According to the disclosed embodiment, the load on the base
station can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagram showing one example of a radio
communication system;
[0010] FIG. 2 is a functional block diagram showing one example of
an eNodeB;
[0011] FIG. 3 is a diagram showing one example of transmission of
system information;
[0012] FIG. 4 is a flowchart showing one example of operations of
the eNodeB; and
[0013] FIG. 5 is a diagram showing the example of the operations of
the eNodeB.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0014] Next, a configuration for implementing the present invention
is explained based on the following embodiment, while referring to
the drawings. Here, in all the drawings for explaining the
embodiment, the same reference numerals are used for entities
having the same functions, thereby omitting repeated
explanations.
Embodiment
[0015] <Radio Communication System>
[0016] FIG. 1 is one example of a radio communication system.
[0017] The radio communication system includes a base station (eNB:
eNodeB) 200 and a user terminal (UE: User Equipment) 100.sub.n (n
is an integer such that n>0). FIG. 1 shows the example where
n=5.
[0018] A Mobility Management Entity (MME)/Serving-Gateway (S-GW)
(not shown) is installed at an upper level of the eNodeB 200. The
MME/S-GW is included in a core network, and the MME/S-GW terminates
a non-access stratum (NAS). The MME/S-GW manages user equipment in
an idle state, and the MME/S-GW manages System Architecture
Evolution (SAE) bearer resources. The MME/S-GW may be referred to
as a "core node."
[0019] The eNodeB 200 causes an uplink signal to the eNodeB 200 to
be barred for a predetermined case. Further, the eNodeB 200 may
cause uplink signals to the eNodeB 200 to be decreased for the
predetermined case. The predetermined case includes a case where
the eNodeB 200 is congested.
[0020] When the eNodeB 200 bars the uplink signal to the eNodeB
200, the eNodeB 200 performs the following processing.
[0021] The eNodeB 200 bars the uplink signal to the eNodeB 200 by
switching a target of barring. By switching the target of the
barring, the user equipment which corresponds to the target of the
barring is switched. Thus, an uplink signal from each of the user
terminals can be evenly barred.
[0022] <Example of Target of Barring>
[0023] <Cell>
[0024] The target of the barring includes a cell.
[0025] An area which is covered by the eNodeB 200 includes one or
more cells 250.sub.m (m is an integer such that m>0). In the
example shown in FIG. 1, the area covered by the eNodeB 200
includes a cell 250.sub.1, a cell 250.sub.2, and a cell 250.sub.3.
The area which is covered by the eNodeB 200 may be one or two
cells, or the area covered by the eNodeB 200 may be four or more
cells. The cells 250.sub.1, 250.sub.2, and 250.sub.3 may be
referred to as "sectors." The cells include cells where radio
communications are possible on the same frequency bands, and cells
where radio communications are possible on different frequency
bands. Specifically, a plurality of the cells that is covered by
the eNodeB 200 is set to, be the targets of the barring. Namely,
among the cells, the cell which is the target of the barring is
sequentially switched. When the cell which is the target of the
barring is sequentially switched, the cell which is to be barred
may be specified by a frequency band. Alternatively, a sector which
is to be the target of the barring may be specified.
[0026] Further, the cell which is covered by the eNodeB 200 may be
switched in an eNodeB 200 by eNodeB 200 basis. Specifically, a cell
which is covered by a plurality of the eNodeBs may be switched. The
switching of the cell, which is on the eNodeB by eNodeB basis, may
be performed by an apparatus having an operation, administration,
and maintenance (OAM) function on a network.
[0027] <Type of Call>
[0028] The target of the barring includes a type of a call.
[0029] Specifically, the types of calls include mobile originated
(MO) signaling from the user equipment 100.sub.n, a mobile
originated call (MO data) from the user equipment 100.sub.n, and a
circuit switch (CS) service.
[0030] The mobile originated signaling from the user equipment
100.sub.n includes location registration and "Attach."
[0031] The eNodeB 200 switches the type of the call as the target
of the barring. For switching the type of the call, the subject of
the barring may be switched in a predetermined order among the
mobile originated signaling from the user equipment 100.sub.n; the
mobile originated call from the user equipment 100.sub.n, and the
circuit switch service. The subject of the barring may be randomly
switched.
[0032] The mobile originated signaling from the user equipment
100.sub.n is barred by switching the target of the barring to be
the mobile originated signaling from the user equipment 100.sub.n.
Namely, an attach request signal is not transmitted from the user
equipment 100.sub.n, even for a case where a user turns on a power
supply of the user equipment 100.sub.n and the attach request
signal is to be transmitted under a normal circumstance. Further, a
location registration signal is not transmitted from the user
equipment 100.sub.n, even for a case where a location registration
area of the user equipment 100.sub.n is changed and the location
registration signal is to be transmitted under a normal
circumstance. The mobile originated call from the user equipment
100.sub.n is described when the target of the barring is switched
to the mobile originated call from the user equipment 100.sub.n.
Namely, a signal which is to be transmitted during the mobile
originated call from the user equipment 100.sub.n is not
transmitted, even if the user performs an operation for the mobile
originated call. The user equipment 100.sub.n may indicate that the
mobile originated call is barred. Specifically, when the user
performs the operation for the mobile originated call, indication
may be made that the mobile originated call is barred. The eNodeB
200 may avoid performing the process which is for the signal to be
transmitted during the mobile originated call, even if the user
performs the operation for the mobile originated call, and the
signal, which is to be transmitted during the mobile originated
call, is transmitted from the user equipment 100.sub.n.
[0033] Further, the target of the barring may be switched to an
incoming call toward the user equipment 100.sub.n. The incoming
call toward the user equipment 100.sub.n is barred by switching the
target of the barring to the incoming call toward the user
equipment 100.sub.n. Namely, an incoming call toward the user
equipment 100.sub.n by another user is not received, even if the
other user performs an operation for the incoming call toward the
user equipment, which is the target of the barring. A notification
may be made that the incoming call is barred. Specifically, when
the operation for the incoming call is performed by the other user,
a notification may be made that the destination user equipment is
barred. The eNodeB 200 may avoid performing the process
corresponding to a signal which is to be transmitted during the
incoming call, even if the other user performs the operation for
the incoming call, and the signal, which is to be transmitted
during the incoming call, is transmitted from the user equipment
100.sub.n of the other user.
[0034] When the target of the barring is switched to the circuit
switch service, the circuit switch service of the user equipment
100.sub.n is barred. For the user equipment 100.sub.n, the circuit
switch service is barred. However, the user equipment 100.sub.n can
perform communication by a packet switch service.
[0035] <Types of User Equipment>
[0036] The targets of the barring include types of the user
equipment 100.sub.n.
[0037] Specifically, the types of the user equipment 100.sub.n may
include user equipment of a general user; user equipment of a user
who is preferentially connected; and user equipment of a person who
performs maintenance or the like. The types of the user equipment
may be specified by an access class.
[0038] By switching the target of the barring to be the user
equipment of the general user, communication from the user
equipment of the general user is barred. When the communication
from the user equipment of the general user is barred, a signal
from the user equipment of the general user is not transmitted to
the eNodeB 200. Further, a signal may be prevented from being
transmitted from the eNodeB 200 to the user equipment of the
general user.
[0039] By switching the target of the barring to be the user
equipment of the user who is preferentially connected,
communication from the user equipment of the user who is
preferentially connected is barred. When the communication from the
user equipment of the user who is preferentially connected is
barred, a signal from the user equipment of the user who is
preferentially connected is not transmitted to the eNodeB 200.
Further, a signal may be prevented from being transmitted from the
eNodeB 200 to the user equipment of the user who is preferentially
connected.
[0040] By switching the target of the barring to the user equipment
of the person who performs maintenance or the like, communication
from the user equipment of the person who performs maintenance or
the like is barred. When the communication from the user equipment
of the person who performs maintenance or the like is barred, a
signal from the user equipment of the person who performs
maintenance or the like is not transmitted to the eNodeB 200.
Further, a signal may be prevented from being transmitted from the
eNodeB 200 to the user equipment of the person who performs
maintenance or the like.
[0041] It is preferable that a frequency of switching the target of
the barring to be the user equipment of the user who is
preferentially connected be smaller than a frequency of switching
the target of the barring to be the user equipment of the general
user, and a frequency of switching the target of the barring to be
the user equipment of the person who performs maintenance or the
like. That is because the user is to be preferentially connected
compared to the general user or the person who performs maintenance
or the like.
[0042] <Function of eNodeB>
[0043] FIG. 2 shows an embodiment of the eNodeB 200.
[0044] The eNodeB 200 includes a congestion state determination
unit 202. The congestion state determination unit 202 determines
whether the eNodeB 200 is in a congestion state, based on
information for determining the congestion state of the eNodeB 200
(which is referred to as the "congestion state determination
information," hereinafter). Specifically, information indicating a
utilization rate of a CPU (which is referred to as the "CPU
utilization rate," hereinafter), which is installed in the eNodeB
200, is input to the congestion state determination unit 202 as the
congestion state determination information. The congestion state
determination unit 202 may determine whether the eNodeB 200 is in
the congestion state, based on the CPU utilization rate. When a
plurality of the CPUs is installed, an average value may be used.
Alternatively, among CPU utilization rates, the maximum value or
the minimum value of the CPU utilization rates may be used.
Additionally, the CPU utilization rate may be calculated by
performing predetermined statistical processing.
[0045] Further, a degree (level) of the congestion may be
determined based on the CPU utilization rate. When the congestion
state determination unit 202 determines that the eNodeB 200 is in a
congestion state, the congestion state determination unit 202
reports to a barring target setting unit 204 and a barring time
interval setting unit 206 that the state is the congestion state.
The level of the congestion and the congestion state may be
reported together. By reporting the level of the congestion, the
congestion state may be reported. As the level of the congestion,
the CPU utilization rate may be reported.
[0046] The eNodeB 200 includes the barring target setting unit 204.
The barring target setting unit 204 is connected to the congestion
state determination unit 202. When the congestion state
determination unit 202 reports to the barring target setting unit
204 that the eNodeB 200 is in the congestion state, the barring
target setting unit 204 sets a target to be barred. Specifically,
it is selected among a cell, a type of a call, and a type of user
equipment. One of the cell, the type of the call, and the type of
the user equipment may be selected. Two or more of the cell, the
type of the call, and the type of the user equipment may be
selected. All of the cell, the type of the call, and the type of
the user equipment may be selected. Among the cell, the type of the
call, and the type of the user equipment, an order of selecting the
target to be barred may be defined in advance. The barring target
setting unit 204 selects the target to be barred in accordance with
the order.
[0047] The barring target setting unit 204 defines a subject of the
barring for the selected target of the barring.
[0048] Specifically, when the cell is selected as the target of the
barring, a frequency of a cell to be barred and the cell to be
barred may be defined as the subjects to be barred. When the cell
is switched as the target of the barring on an eNodeB-by-eNodeB
basis, and when the eNodeB is the target of the barring, the
barring target setting unit 204 may set it to be all the cells
within the eNodeB, which is the target of the barring. Namely, when
a device having the operation, administration, and maintenance
function on the network reports that the eNodeB is the target of
the barring, the barring target setting unit 204 may set that all
the cells included in the eNodeB are the target cells to be
barred.
[0049] When the type of the call is selected as the target of the
barring, the subject of the barring may be selected among a
transmission signal from user equipment, a call originating from
user equipment, and a circuit switch service. One of, two of, or
all of the transmission signal from the user equipment, the call
originating from the user equipment, and the circuit switch service
may be selected.
[0050] When the type of the user equipment is selected as the
target of the barring, the subject of the barring may be selected
among the user equipment of the general user, the user equipment of
the user who is preferentially connected, and the user equipment of
the person who performs maintenance or the like. One of, two of, or
all of the user equipment of the general user, the user equipment
of the user who is preferentially connected, and the user equipment
of the person who performs maintenance or the like may be
selected.
[0051] The barring target setting unit 204 inputs information
representing the target of the barring and information representing
the subject of the barring to a system information editing unit
208.
[0052] The eNodeB 200 includes the barring time interval setting
unit 206. The barring time interval setting unit 206 is connected
to the congestion state determination unit 202. When the barring
time interval setting unit 206 is informed by the congestion state
determination unit 202 that the eNodeB 200 is in the congestion
state, the barring time interval setting unit 206 sets a time
interval of the barring. Specifically, the time interval of the
barring may be defined in a single uniform way, and the thus
defined time interval may be set. Alternatively, the time interval
of the barring may be selected depending on the level of the
congestion. The time interval of the barring is elongated, when the
level of the congestion is large. That is because it is assumed
that a longer time interval is required for resolving the
congestion, when the level of the congestion is large. In other
words, the time interval of the barring is elongated, when the CPU
utilization rate is large. Specifically, as time intervals of the
barring, selection candidates may be defined in advance.
Concretely, the barring time interval setting unit 206 may select
the time interval of the barring among 1, 5, 10, 20, 30, and 60
seconds. The barring time interval setting unit 206 inputs
information representing the time interval of the barring to the
system information editing unit 208.
[0053] The eNodeB 200 includes the system information editing unit
208. The system information editing unit 208 is connected to the
barring target setting unit 204 and to the barring time interval
setting unit 206. The barring target setting unit 204 inputs
information representing the target of the barring and information
indicating the subject of the barring to the system information
editing unit 208. Further, the barring time interval setting unit
206 inputs information representing the time interval of the
barring to the system information editing unit 208.
[0054] When the information representing the target of the barring,
the information indicating the subject of the barring, and the
information representing the time interval of the barring are
input, the system information editing unit 208 includes information
which indicates that broadcast information is changed in a paging
message. Namely, when the information representing the target of
the barring, the information indicating the subject of the barring,
and the information representing the time interval of the barring
are input, system information is changed. Thus, a
systemInfoModification Information Element is included in the
paging message.
[0055] Further, the system information editing unit 208 edits the
system information which includes the information representing the
target of the barring, which is input by the barring target setting
unit 204; the information representing the subject of the barring,
which is input by the barring target setting unit 204; and the
information representing the time interval of the barring, which is
input by the barring time interval setting unit 206. Namely, the
system information editing unit 208 updates a systemInfoValueTag IE
of a system information block 1 (SIB1).
[0056] The system information editing unit 208 inputs the paging
message and the system information to a transmitter 210.
[0057] The eNodeB 200 includes the transmitter 210. The transmitter
210 is connected to the system information editing unit 208. The
transmitter 210 transmits the paging message, which is input by the
system information editing unit 208. The paging message includes
the information indicating that the broadcast information is
changed. Additionally, the transmitter 210 transmits the system
information, which is input by the system information editing unit
208.
[0058] <Example of Transmission of the System
Information>
[0059] FIG. 3 shows an example of transmission of the system
information. In FIG. 3, a horizontal axis represents time. The
broadcast channel which is transmitted by the eNodeB 200 is changed
in a unit of a broadcast control channel (BCCH) modification
period. In the example shown in FIG. 3, notification is made that
the information included in the system information is to be changed
(Change notification) in a BCCH modification period (L).
Notification of the system information including the changed
information (Updated information) is made in a BCCH modification
period (L+1).
[0060] The transmitter 210 transmits the paging message from the
system information editing unit 208. The paging message includes
the systemInforModification Information Element. The transmitter
210 may transmit the paging message which is specified so that it
is received by all units of the user equipment. The transmitter 210
may transmit the paging message which specifies units of the user
equipment which are to receive the paging message.
[0061] Specifically, when a cell is selected as the target of the
barring, and when the cell which is to be barred is specified by a
frequency band, units of the user equipment which perform radio
communication in the frequency band may be specified by the paging
message. When a cell is selected as the target of the barring, and
when the cell which is to be barred is specified by a sector, units
of the user equipment which perform radio communication in the
sector may be specified by the paging message. When a cell which is
covered by the eNodeB 200 is switched in a unit of the eNodeB 200,
units of the user equipment which perform radio communication in
the cell which is covered by the eNodeB 200 may be specified by the
paging message.
[0062] When a type of a call is selected as the target of the
barring, units of the user equipment which perform radio
communication in a cell which is covered by the eNodeB 200 may be
specified by the paging message.
[0063] When a type of user equipment is selected as the target of
the barring, units of the user equipment which are to be barred may
be specified by the paging message.
[0064] By transmitting the paging message, a notification can be
made to the user equipment 100 that the system information is
changed.
[0065] The transmitter 210 transmits the system information. The
transmitter 210 transmits system information including the same
information during the BCCH modification period, in units of the
BCCH modification period. The system information is transmitted so
that it is received by units of the user equipment, which are the
targets of the barring.
[0066] Specifically, when a cell is selected as the target of the
barring, and the cell which is to be barred is specified by a
frequency band, the system information is transmitted in the
frequency band to the cell which is the target of control. When a
cell is selected as the target of the barring, and the cell which
is to be barred is specified by a sector, the system information is
transmitted within the sector. Further, when a cell which is
covered by the eNodeB 200 is switched in a unit of the eNodeB 200,
the system information is transmitted in a cell which is the target
of the control among the cells which are covered by the eNodeB
200.
[0067] When a type of a call is selected as the target of the
barring, the system information is transmitted in a cell which is
the target of the control among the cells which are covered by the
eNodeB 200.
[0068] When a type of user equipment is selected as the target of
the barring, the system information is transmitted in a cell which
is the target of the control among the cells which are covered by
the eNodeB 200.
[0069] When there is a plurality of targets of the barring, the
system information may be transmitted in an overlapped area among
areas. Here, in each of the areas, the system information
corresponding to the target of the barring is to be transmitted.
Alternatively, when there is the plurality of the targets of the
barring, the system information pieces may be transmitted in all
the corresponding areas in which the system information pieces are
to be transmitted.
[0070] In the example shown in FIG. 3, the transmitter 210
transmits system information including the same information four
times in the BCCH modification period. The transmitter 210
continues transmitting the system information, which is transmitted
when the system information is input from the system information
editing unit 208, until the expiration of the BCCH modification
period. After the expiration of the BCCH modification period, the
transmitter 210 transmits the system information including the
modified information in the next BCCH modification period.
[0071] <Operations of the eNodeB>
[0072] FIG. 4 shows an example of operations of the eNodeB 200. In
FIG. 4, N represents an identification number of a cell, and G
represents a number of the cells included in the eNodeB 200. Here,
G may be a number of cells which are targets of the barring in the
eNodeB 200. That is because it is possible that the cells which are
to be the targets of the barring are a part of the cells which are
controlled by the eNodeB.
[0073] As an example of the operations of the eNodeB 200, a case is
shown in which a mobile originated call from user equipment of a
general user is barred on a cell-by-cell basis.
[0074] The eNodeB 200 measures the congestion state (step S402).
Namely, the eNodeB 200 requests the congestion state determination
information. The process of requesting the congestion state
determination information may be performed regularly, or
irregularly. Specifically, the CPU utilization rate is
requested.
[0075] The eNodeB 200 determines whether it is the congestion state
(step S404). Namely, the congestion determination unit 202
determines whether the eNodeB 200 is in the congestion state, based
on the congestion state determination information, which is
requested at step S402.
[0076] When a determination is made that it is not the congestion
state (step S404: NO), the process returns to step S402. Namely,
the process of switching the target of the barring is not
performed. Since the process of switching the target of the barring
is not performed, an amount of signals which are transmitted and
received between the eNodeB 200 and the user equipment 100.sub.n is
not barred.
[0077] When a determination is made that it is the congestion state
(step S404: YES), the eNodeB 200 selects a target of the barring
(step S406). The target of the barring may be selected based on a
congestion level. Namely, the barring target setting unit 204
selects a target of the barring, among the cell, the type of the
call, and the type of the user equipment. One of the cell, the type
of the call, and the type of the user equipment may be selected, or
two or more of them may be selected.
[0078] When the cell is set to be the target of the barring, a
frequency band of the cell or a sector may be selected as the
subject of the barring. Both the frequency band of the cell and the
sector may be selected.
[0079] When the frequency band of the cell is selected as the
subject of the barring, the frequency band of the cell, which is to
be barred, is sequentially switched, and the cell corresponding to
the frequency band is barred. When the sector is selected as the
subject of the barring, the sector is sequentially switched. When
the eNodeB is selected as the subject of the barring, the area
covered by the eNodeB is barred.
[0080] When the type of the call is set to be the target of the
barring, the subject of the barring may be selected among mobile
originated signaling from user equipment, a mobile originated call
from user equipment, and a circuit switch service. One of the
mobile originated signaling from the user equipment, the mobile
originated call from the user equipment, and the circuit switch
service may be selected, or more than one of them may be
selected.
[0081] When the type of the user equipment is set to be the target
of the barring, the subject of the barring may be selected among
user equipment of a general user, user equipment of a user who is
preferentially connected, and user equipment of a person who
performs maintenance or the like. One of the user equipment of the
general user, the user equipment of the user who is preferentially
connected, and the user equipment of the person who performs
maintenance or the like may be selected, or more than one of them
may be selected.
[0082] When the type of the user equipment is set to be the target
of the barring, a setting may be made so that communication from
user equipment of a general user is to be barred, as the subject of
the barring. Depending on necessity, the communication from the
user equipment of the user who is preferentially connected may be
barred, or the communication from the user equipment of the person
who performs maintenance or the like may be barred.
[0083] In the example shown in FIG. 4, the cell and the type of the
user equipment are selected as the targets of the barring. Further,
when the target of the barring is the cell, the sector is selected
as the subject of the barring. When the target of the barring is
the type of the user equipment, the user equipment of the general
user is selected as the subject of the barring.
[0084] The eNodeB 200 sets a time interval of the barring, based on
the congestion level (step S408). Namely, the barring time interval
setting unit 206 sets a time interval of regulating the target of
the barring, where the target of the barring is selected by the
barring target setting unit 204. A defined time interval may be set
in a single uniform way, or the time interval of the barring may be
set depending on the congestion level. Specifically, for a case
where the time interval of the barring is set depending on the
congestion level, a table (not shown) may be prepared in which the
congestion level is associated with the time interval of the
barring. Further, for each of the targets of the barring, a table
may be prepared, in which a congestion level is associated with a
time interval of the barring. By preparing the table for each of
the targets of the barring, different time intervals of the barring
may be set for the corresponding targets of the barring.
[0085] For the example shown in FIG. 4, the time interval of the
barring is selected to be 5 seconds.
[0086] The eNodeB 200 inserts system information modification into
the paging message (step S410). Namely, the system information
editing unit 208 inserts the system information modification, which
indicates that the system information is modified, into the paging
message. Here, the paging message is to be transmitted prior to the
system information.
[0087] The eNodeB 200 edits the system information (step S412).
Namely, the system information editing unit 208 edits the system
information including information representing the sector which is
the target of the barring; information representing that the mobile
originated call from the user equipment of the general user is to
be barred; and information representing the time interval of the
barring.
[0088] The eNodeB 200 sets N, which represents the identifier
(identification number) of the cell, to be 1 (step S414). Namely,
the barring target setting unit 204 and the barring time interval
setting unit 206 set N, which represents the identification number
of the cell, to be 1.
[0089] The eNodeB 200 transmits the paging message to the user
equipment units in an Nth cell, which is represented by the
identification number of N (step S416). Namely, the transmitter 210
transmits the paging message in the Nth cell. By transmitting the
paging message, a notification can be made to the user equipment
units in the Nth cell that the system information including the
modified information is to be transmitted, subsequent to the
termination of the current BCCH modification period.
[0090] The eNodeB 200 transmits the modified system information in
the Nth cell (step S418). Namely, the transmitter 210 transmits the
system information in the Nth cell. By transmitting the system
information, the system information can be transmitted to the user
equipment in the Nth cell.
[0091] The eNodeB 200 determines whether N, which represents the
identification number of the cell, is equal to G, which represents
the number of the cells (step S420). Namely, the barring target
setting unit 204 and the barring time interval setting unit 206
determine whether N, which represents the identification number of
the cell, is equal to G, which represents the number of the
cells.
[0092] When a determination is made that N, which represents the
identification number of the cell, is equal to G, which represents
the number of the cells (step S420: YES), the process terminates.
The process may return to step S402, and the process of measuring
the congestion state may be restarted. The process of measuring the
congestion state may be performed regularly or irregularly.
[0093] When a determination is made that N, which represents the
identification number of the cell, is not equal to G, which
represents the number of the cells (step S420: NO), the eNodeB 200
sets current N to be the number obtained by adding 1 to N (step
S422), and the process returns to step S416. Namely, the barring
target setting unit 204 and the barring time interval setting unit
206 set the current N to be the number which is obtained by adding
1 to N, and continue the same process until N, which represents the
identification number of the cell, becomes equal to G, which
represents the number of the cells.
[0094] The processes of steps S402-S422 are executed by a central
processing unit (not shown) which is included in the eNodeB 200. A
program that causes the central processing unit to function as the
eNodeB 200 may be provided in a state where the program is stored
in a recording medium such as a flexible disk, a CD-ROM, a memory
card, and the like. Further, the program may be downloaded through
a communication network (not shown). When the recording medium is
inserted into an auxiliary storage device of a computer, the
program which is stored in the recording medium is read out. The
central processing unit writes the read program in a RAM-or in a
HDD, and executes the process. The program causes the computer to
execute each of steps S402-S422 of FIG. 4. Alternatively, for
example, the program may cause at least a part of the steps to be
executed.
[0095] In the flowchart shown in FIG. 4, the order of step S408,
step S410, and step S412 may be changed, or step S408, step S410,
and step S412 may be simultaneously performed.
[0096] FIG. 5 shows operations of the eNodeB 200. The eNodeB 200
executes the processes in accordance with the flowchart shown in
FIG. 4.
[0097] A mobile originated call from user equipment of a general
user in a cell #1 is barred for five seconds. Subsequent to the
barring of the mobile originated call from the user equipment of
the general user in the cell #1, a mobile originated call from user
equipment of a general user in a cell #2 is barred for five
seconds. Subsequent to the barring of the mobile originated call
from the user equipment of the general user in the cell #2, a
mobile originated call from user equipment of a general user in a
cell #3 is barred for five seconds.
[0098] Since the cell, in which the mobile originated call from the
user equipment of the general user is barred, is sequentially
switched, uplink signals from each of the units of user equipment
can be equally barred.
[0099] In the above-described example, as the target of the
barring, the cell, the type of the call, and the type of the user
equipment, may be selected, while they include other items.
[0100] According to the above-described example, when the eNodeB is
congested, uplink signals to the eNodeB can be barred by switching
the target of the barring.
[0101] With respect to the embodiment including the above-described
example, the following items are further disclosed.
[0102] (1) A base station performs radio communication with user
equipment. The base station includes a congestion state
determination unit that determines whether the base station is in a
congestion state; a barring target setting unit that sequentially
sets targets of barring among a plurality of the targets of the
barring when the congestion state determination unit determines
that the base station is in the congestion state; a barring time
interval setting unit that sets a time interval of the barring
based on the congestion state when the congestion state
determination unit determines that the base station is in the
congestion state; a notification information generating unit that
generates information for transmitting information which represents
the targets of the barring and information which represents the
time interval of the barring, wherein the targets of the barring
are to be set by the barring target setting unit, and the time
interval of the barring is to be set by the barring time interval
setting unit; and a transmitter that transmits the information
generated by the notification information generating unit to the
user equipment.
[0103] (2) In the base station described in (1), the barring target
setting unit may select the targets of the barring among a cell, a
type of a call, and a type of the user equipment.
[0104] (3) In the base station described in (2), when the barring
target setting unit selects the cell as the target of the barring,
the barring target setting unit may specify the cell, which is to
be barred, by at least one of a frequency and an identifier of the
cell.
[0105] (4) In the base station described in (2), when the barring
target setting unit selects the type of the call as the target of
the barring, the barring target setting unit may specify the type
of the call by at least one of a mobile originated call from the
user equipment, mobile originated signaling from the user
equipment, and a circuit switch service, wherein the type of the
call is to be barred.
[0106] (5) In the base station described in (2), when the barring
target setting unit selects the type of the user equipment as the
target of the barring, the barring target setting unit may specify
the user equipment by at least one of the user equipment of a
general user, the user equipment of a user who is preferentially
connected, and the user equipment of a person who performs
maintenance, wherein the type of the user equipment is to be
barred.
[0107] (6) In the base station described in (1), the notification
information generating unit may generate system information
including information for transmitting a paging message which
includes information indicating that broadcast information is
modified; information which represents the targets to be barred,
wherein the targets to be barred are to be set by the barring
target setting unit; and information representing the time interval
of the barring, wherein the time interval of the barring is to be
set by the barring time interval setting unit.
[0108] (7) A communication control method is a method of a base
station that performs radio communication with user equipment. The
communication control method includes a congestion state
determination step of determining whether the base station is in a
congestion state; a barring target setting step of sequentially
setting targets of barring among a plurality of the targets of the
barring when the congestion state determination step determines
that the base station is in the congestion state; a barring time
interval setting step of setting a time interval of the barring
based on the congestion state when the congestion state
determination step determines that the base station is in the
congestion state; a notification information generating step of
generating information for transmitting information which
represents the targets of the barring and information which
represents the time interval of the barring, wherein the targets of
the barring are to be set by the barring target setting step, and
the time interval of the barring is to be set by the barring time
interval setting step; and a transmission step of transmitting the
information generated by the notification information generating
step to the user equipment.
[0109] For the convenience of the explanation, specific examples of
numerical values are used in order to facilitate understanding of
the invention. However, these numerical values are simply
illustrative, and any other appropriate values may be used, except
as indicated otherwise.
[0110] Hereinabove, the present invention is explained by referring
to the specific embodiments. However, the embodiments are merely
illustrative, and variations, modifications, alterations and
substitutions could be conceived by those skilled in the art. For
the convenience of the explanation, the devices according to the
embodiment of the present invention are explained by using
functional block diagrams. However, these devices may be
implemented in hardware, software, or combinations thereof. The
present invention is not limited to the above-described embodiment,
and various variations, modifications, alterations, substitutions
and so on are included, without departing from the spirit of the
present invention.
[0111] The present application is based on and claims the benefit
of priority of Japanese Patent Application No. 2011-098678 filed on
Apr. 26, 2011, the entire contents of which are hereby incorporated
by reference.
LIST OF REFERENCE SYMBOLS
[0112] 100.sub.n (n is an integer such that n>0): User
equipment
[0113] 200: eNodeB
[0114] 202: Congestion state determination unit
[0115] 204: Barring target setting unit
[0116] 206: Barring time interval setting unit
[0117] 208: System information editing unit
[0118] 210: Transmitter
[0119] 250.sub.m (m is an integer such that m>0): Cell
* * * * *